Apparatus and method for generating a power delivery network

ABSTRACT

An apparatus and method for generating a power delivery network (PDN) of a circuit system is provided. The apparatus performs a power diagnostics on the PDN of a circuit system. According to result of the power diagnostics, a number of areas are generated and divided into at least three subsets. At least one area is selected from each of the at least three subsets, and one node is selected from each of the selected areas, and the nodes are connected orderly to form an interconnection with at least three nodes in the PDN.

This application claims the benefit of Taiwan application Serial No.103101319, filed Jan. 14, 2014, the disclosure of which is incorporatedby reference herein in its entirety.

TECHNICAL FIELD

The disclosure relates in general to apparatus and method for generatinga power delivery network.

BACKGROUND

There are many researches related to the design of power deliverynetwork (Power Delivery Network, or Power Distribution Network, or PowerNetwork, hereinafter all referred to as “PDN”). Generally speaking,there are many nodes in the PDN. The quality of PDN are mainlyinfluenced by the resistance of the transmission line, i.e. when currentflowing through a section of the transmission line, because of thepresence the resistance, the voltage drop would be generated. Thevoltage drop is also known as IR drop (“I” represents current and “R”represents resistance). The voltage drop would lower the stability ofthe circuit system, and even cause the error of the circuit. Forexample, in an integrated circuit (IC), large voltage drop happened inthe PDN would cause malfunction of the IC. And, the quality of the PDNwould influence the power integrity (PI) of the IC.

Normally, the design of the PDN would be in uniform type. For example,horizontal/vertical power stripes of the PDN have the same spacing andwidth. Owing to the large voltage drop, the power supply may be notenough since different areas have different power supply requirements.Or, the power supply would be overdesigned which wasting signal windingresources. To avoid the above issues are engaged by industry.

FIG. 1 illustrates a flow diagram of a current integrated circuit design(hereinafter referred to as “IC design”). The current IC design includescircuit design step 102, floorplan and PDN design step 104, circuit unitplacement and clock tree generation step 106, routing step 108, andpower analysis step 110. After power analysis step 110, if it isnecessary to provide power distribution network adjustment, the designershould go back to the floorplan and PDN design step 104 from poweranalysis step 110 to redesign the PDN, for instance, to increase thedense of the PDN or to widen the line width of the PDN or to increasethe numbers of the power sources. When redesigning, step 104 to step 110should be repeated with lengthy turn-around time. The total IC designtime will be lengthened. If the designer repeats redesigning for severaltimes, it may cause a significant delay in the IC design process.

SUMMARY

According to one embodiment, an apparatus for generating a PDN of acircuit system is provided. The apparatus may comprise a power analyzerconfigured to perform a first power diagnostics on the PDN of thecircuit system and generate a number of areas according to the result ofthe first power diagnostics. The areas may be divided into at leastthree subsets. At least one area may be selected from each of the atleast three subsets, one node may be selected form each of the selectedareas. The nodes are connected orderly to form an interconnection withat least three nodes in the PDN.

According to an alternative embodiment, a method for generating a PDN ofa circuit system is provided. The method may perform a first powerdiagnostics on the PDN of the circuit system and generate a number ofareas according to the result of the first power diagnostics. The areasmay be divided into at least three subsets. At least one area may beselected from each of the at least three subsets. One node may beselected form each of the selected areas. The nodes may be connectedorderly to form an interconnection with at least three nodes in the PDN.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a flow diagram of a current integrated circuitdesign.

FIG. 2 illustrates an exemplary flow diagram of a method for generatinga PDN according to an embodiment of the disclosure.

FIG. 3 shows a flow diagram of circuit system design with applying themethod for generating the PDN in FIG. 2.

FIG. 4 illustrates one example, in which a number of exemplaryinterconnections or paths are shown according to an exemplaryembodiment.

FIG. 5 illustrates exemplary target areas for generating a PDN accordingto an exemplary embodiment.

FIG. 6 illustrates an exemplary method of producing subsets according toan exemplary embodiment.

FIGS. 7A˜7C illustrate an example of producing a number ofinterconnections according to an exemplary embodiment.

FIG. 8 illustrates an example of interconnections in the PDN accordingto an exemplary embodiment.

FIG. 9 illustrates an exemplary block diagram of an apparatus forgenerating a PDN according to an exemplary embodiment

FIG. 10A˜10B illustrate another example of producing interconnectionsaccording to an exemplary embodiment.

In the following detailed description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of the disclosed embodiments. It will be apparent,however, that one or more embodiments may be practiced without thesespecific details. In other instances, well-known structures and devicesare schematically shown in order to simplify the drawing.

DETAILED DESCRIPTION

Below, exemplary embodiments will be described in detail with referenceto accompanying drawings so as to be easily realized by a person havingordinary knowledge in the art. The inventive concept may be embodied invarious forms without being limited to the disclosure set forth herein.Descriptions of well-known parts are omitted for clarity, and likereference numerals refer to like elements throughout.

FIG. 2 illustrates an exemplary flow diagram of a method for generatinga PDN according to an embodiment of the disclosure. First, in step 202,a first power diagnostics is performed on a PDN of a circuit system. Anumber of areas are generated according to the result of the first powerdiagnostics. There is at least one node in each area. After that, theareas are divided into at least three subsets in step 204. Then, in step206, at least one area is selected from each of the at least threesubsets, and one node is selected from each of the selected areas. Thosenodes are connected orderly to form an interconnection with at leastthree nodes in the PDN.

FIG. 3 shows a flow diagram of circuit system design with applying theembodiment of the method for generating the PDN in FIG. 2. The circuitsystem design in FIG. 3 could be an IC design or any other circuitsystem design with PDN. The steps for the circuit system design in FIG.3 includes circuit design step 302, floorplan and PDN design step 304,circuit unit placement and clock tree generation step 306, routing step308, power analysis step 310, and PDN generating step 312. Performing afirst power diagnostics on the PDN in the step 202 is accomplished instep 310. The PDN generating step 312 includes step 204, step 206, andthe other part of step 202. According to the flow of circuit systemdesign of FIG. 3, step 308 is before step 312. Therefore, whengenerating the PDN, it is not necessary to go back to floorplan and PDNdesign step 304 to redesign the PDN and perform steps 306 and 308, whichis time-consuming. The flow of the circuit system design with applyingthe method for generating the PDN of this embodiment could build a PDNof a circuit system by repeating step 310 and step 312. The design timeof the circuit system could be saved greatly. The product of the circuitsystem could go into the market quickly.

To be more detailed, in the step 202 of FIG. 2, a number of areas aregenerated according to the result of the first power diagnostics, andthe locations of the areas and the level of voltage drop would befurther analyzed. In step 204, part or all areas are selected to betarget areas. These target areas are divided into at least threesubsets. Each of the subsets would contain at least one target area. Atleast one target area is selected from each of the at least threesubsets in step 206, and one node is selected from each of the selectedtarget areas and the nodes are connected orderly to form aninterconnection, i.e. PDN path, with at least three nodes in the PDF. Anumber of interconnections or PDN paths can be formed in several targetareas. FIG. 4 shows one example, in which exemplary interconnections orPDN paths include interconnections P1, P2 and P3, for example. Whenforming the interconnections or PDN paths, the target areas to beconnected and the order of connections are taken into consideration.

Base on the above descriptions, the following provides more detaileddescriptions for each step. Assume the range from 0.65 V to 1.0 V isdivided to obtain 7 voltage ranges, as shown in FIGS. 5. 0 V to 0.65 Vis an independent voltage range. Therefore, 8 voltage ranges areobtained. The 8 voltage ranges are referred as 8 voltage drop ranges.(For another exemplary embodiment, the number of the voltage ranges canbe modified. For example, 10 voltage ranges could be used.) Afterperforming the first power diagnostics, 8 areas are produced based onthe 8 voltage ranges. Referring to FIG. 5, there are 8 areas representedby A, B, C . . . , and H in the circuit system. At least 3 target areascould be selected from the areas for PDN generating.

After that, the selected target areas can be divided to at least 3subsets. The following would be an example with 3 subsets. Assume the 8areas are all selected as 8 target areas in FIG. 5. According to thelevel of voltage drop shown in FIG. 6, the 8 target areas are arrangedorderly as target areas A, B . . . H from the most serious level to theleast serious level of voltage drop. A and B target areas belong to thefirst subset. C, D and E target areas belong to the second subset. F, Gand H target areas belong to the third subset. The PDN of the circuitsystem could be divided to 3 subsets orderly according to the level ofvoltage drop. The first subset includes A and B target areas whosevoltage drop levels are most serious. The second subset includes C, Dand E target areas whose voltage drop levels are less serious than thefirst subset. The third subset includes F, G and H target areas whosevoltage drop levels are least serious in this example.

According to the method for generating the PDN in this embodiment of thedisclosure, a PDN interconnection could be formed by selecting at leastone target area from each subset. Referring to FIG. 7A, the selectedtarget areas could be A target area from the first subset, C and Etarget areas from the second subset, and F target area from the thirdsubset. One node could be selected from each of the selected targetareas. Interconnection P1 could be formed by connecting those nodesselected from the selected target areas A, C, E, and F. Theinterconnection P1 passes through the selected target areas F, E, C andA orderly. As showed by FIG. 8, interconnection P1 starts from the thirdsubset, whose voltage drop level is least serious, passes through thesecond subset, whose voltage drop level is less serious, and ends in thefirst subset, whose voltage drop level is most serious.

After that, referring to FIG. 7B, the selected target areas could be Btarget area from the first subset, C target area from the second subset,and G target area from the third subset. One node could be selected fromeach of the selected target areas. Interconnection P2 could be formed byconnecting those nodes selected from the selected target areas B, C, andG. The interconnection P2 passes through the selected target areas G, Cand B orderly. As showed by FIG. 8, interconnection P2 starts from thethird subset, whose voltage drop level is least serious, passes throughthe second subset, whose voltage drop level is less serious, and ends inthe first subset, whose voltage drop level is most serious.

Referring to FIG. 7C, the selected target areas could be A target areafrom the first subset, C target area from the second subset, and Gtarget area from the third subset. One node could be selected from eachof the selected target areas. Interconnection P3 could be formed byconnecting those nodes selected from the selected target areas A, C andG. The interconnection P3 passes through the selected target areas A, Cand G orderly. As showed by FIG. 8, interconnection P3 starts from thefirst subset, whose voltage drop level is most serious, passes throughthe second subset, whose voltage drop level is less serious, and ends inthe third subset, whose voltage drop level is least serious.

Thus, the designer could generate lots of PDN paths with characteristicof order and characteristic of direction according to the level ofvoltage drop and position of the areas to form the PDN. The number ofthe target areas and interconnections could be decided by the designerin this embodiment of the disclosure. The target area is a 2 dimensionalblock, therefore the problem of voltage drop could be handled with theaspect of “surface”. Further, the total circuit units would be the samebecause the existing design of PDN is used in the circuit system forthis disclosure.

FIG. 9 illustrates an exemplary block diagram of an apparatus forgenerating a PDN according to an embodiment. Applying power networkanalyzer 20, PDN device 100 performs a first power diagnostics on a PDN12 of a circuit system 10. A number of areas are generated according tothe result of the first power diagnostics. The areas are divided into atleast three subsets. At least one area is selected from each of the atleast three subsets, one node is selected from each of the selectedareas, and the nodes are connected orderly to form an interconnectionwith at least three nodes in the PDN 12.

According to an exemplary embodiment, the interconnection would have asegment between each two adjacent nodes. The segments could have thesame or different metal width. The interconnection could be formed viaI/O pads, rings, strips, bumps, rails, and through silicon vias (TSV),or a combination thereof. According to another exemplary embodiment, theinterconnection could be vertical metal segment, horizontal metalsegment, and diagonal metal segment, or a combination thereof. Accordingto another exemplary embodiment, the nodes of the interconnection couldbe located in different metal layers as well as the segments. The sameinterconnection could pass through different metal layers. The metallayers are the routing metal layers of the circuit system. According toanother exemplary embodiment, the interconnection could be formedaccording to a circuit design rule or a design rule checking, or furtheraccording a design rule of nodes connection among different metal. Powerdiagnostics includes voltage drop analysis.

According to an exemplary embodiment, power network analyzer 20 couldperform power diagnostics again while a number of interconnections havebeen formed in the target areas. The above steps of forming aninterconnection could be repeated to form another interconnection in thetarget areas. For example, after PDN generating step 312, the designercould go back to power analysis step 310 and perform power diagnosticsagain for the IC having a number of PDN paths. And then, the designercould perform PDN generating step 312 and generate anotherinterconnection. The PDN of the circuit system could be furtherconstructed or compensated by the another interconnection. FIG. 10A andFIG. 10B shows another examples of producing interconnection. Referringto FIG. 10A, the another interconnection could be formed through thenodes of target areas A, C and E. Or, referring to FIG. 10B, theinterconnection could be formed through the nodes of target areas A, C,E and F. After performing the power diagnostics again and generating theareas, the number of areas should be not limited to 8 as shown in FIG.10A and FIG. 10B. The number of areas could be 10, 16, and so on.Performing the power diagnostics and forming the interconnections couldbe executed for many times until the PDN of the circuit system is withsufficient integrity or stability, or until the winding space used up.

Referring to FIG. 9, according to an exemplary embodiment, the areascould be divided into at least 3 subsets based on at least 2 targetvalues. The at least 2 target values could be defined by the userinterface 30, or defined by reading from the storage media 40. The atleast 2 target values are less than the operation voltage. The operationvoltage is between the power source voltage and the ground voltage, oris equal to the power source voltage. In other embodiment, the operationvoltage can be equal to the ground voltage, and the at least 2 targetvalues are larger than the operation voltage (i.e. the ground voltage).In this embodiment, the ground bounce can be efficiently reduced. Thepower network analyzer 20 is used to perform power diagnostics byanalyzing the voltage drop of each node in the PDN of the circuit systemor ground bounce noise or the combination thereof. According to anexemplary embodiment, each of the at least 3 subsets could be furthersubdivided into at least 3 subsets, and the method for generating thePDN paths or interconnections disclosed above can be repeated. That is,the designer could perform power diagnostics again, and select sub-nodesfrom each subset of the subsets to form the interconnections. There isno limitation for the number of times for above steps.

Using integrated circuit as a test carrier to perform an experiment, themethod for generating the PDN of this disclosure is used in thisexperiment. In this experiment, the density of the PDN paths increases16.67% and 32.47%, respectively, for example. However, the presentdisclosure is not limited thereto. The density of the PDN pathsinterconnections could be designed according to the result of the powerdiagnostics. For example, when the density of the PDN paths increases16.67%, the improvement of voltage drop could be 33.08%. When thedensity of the PDN paths increases 32.47%, the improvement of voltagedrop could be up to 36.72%. Thus, the proposed method and apparatus ofthis disclosure could avoid the time-consuming redesign of PDN, reducethe design time of IC design and make the product of IC go to the marketearlier, reduce the voltage drop of the PDN effectively, and enhance theoverall stability and quality of PDN.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed embodiments.It is intended that the specification and examples be considered asexemplary only, with a true scope of the disclosure being indicated bythe following claims and their equivalents.

What is claimed is:
 1. An apparatus for generating a PDN (power deliverynetwork) of a circuit system, the apparatus comprising: a poweranalyzer, configured to perform a first power diagnostics on the PDN ofthe circuit system and generate a plurality of areas according to theresult of the first power diagnostics; wherein the areas are dividedinto at least three subsets; wherein at least one area is selected fromeach of the at least three subsets, one node is selected form each ofthe selected areas, and the nodes are connected orderly to form aninterconnection with at least three nodes in the PDN.
 2. The apparatusaccording to claim 1, wherein the apparatus further comprising a userinterface or a storage media, and the areas are divided into the atleast three subsets according to at least two target values, the atleast two target values are defined by the user interface or defined byreading from the storage media.
 3. The apparatus according to claim 2,wherein the at least two target values are less than an operationvoltage of the PDN and the operation voltage is between a power sourcevoltage and a ground voltage, or is substantially equal to the powersource voltage, or the operation voltage of the PDN is substantiallyequal to the ground voltage, and the at least 2 target values are largerthan the operation voltage.
 4. The apparatus according to claim 1,wherein the power analyzer is used to perform the first powerdiagnostics by analyzing at least one of voltage drops of the PDN and aground bounce noise.
 5. The apparatus according to claim 1, wherein theinterconnection has a segment between each two adjacent nodes, and thesegments have the same or different metal width, and the interconnectioncomprises horizontal metal segment, vertical metal segment, diagonalmetal segment, or the combination thereof.
 6. The apparatus according toclaim 1, wherein the nodes of the interconnection are located indifferent metal layers.
 7. The apparatus according to claim 1, whereineach of the at least three subsets are further divided into at leastthree subsets.
 8. The apparatus according to claim 1, wherein the nodesof the interconnection are selected from the group consisting of I/Opads, rings, strips, bumps, rails, Through silicon vias, and thecombination thereof.
 9. The apparatus according to claim 1, wherein theinterconnection is formed according to a circuit design rule or a designrule checking, or further according to a design rule of nodes connectionamong different metals.
 10. The apparatus according to claim 1, whereinthe power analyzer performs a second power diagnostics after theinterconnection is formed, and another interconnection is generated withat least three nodes connected orderly in the PDN accordingly.
 11. Theapparatus according to claim 1, wherein the nodes of the interconnectionare connected according to the order of the areas, and theinterconnection has the characteristics of a surface.
 12. An method forgenerating a PDN of a circuit system, the method comprising: performinga first power diagnostics on the PDN of the circuit system; generating aplurality of areas according to the result of the first powerdiagnostics; dividing the areas into at least three subsets; andselecting at least one area from each of the at least three subsets,selecting one node from each of the selected areas, and connecting thenodes orderly to form an interconnection with at least three nodes inthe PDN.
 13. The method according to claim 12, wherein the methodfurther comprises defining at least two target values and dividing theareas into the at least three subsets according to at least two targetvalues, the at least two target values are defined by a user interfaceor defined by reading from a storage media.
 14. The method according toclaim 13, wherein the at least two target values are less than anoperation voltage of the PDN and the operation voltage is between apower source voltage and a ground voltage, or is substantially equal tothe power source voltage, or the operation voltage of the PDN issubstantially equal to the ground voltage, and the at least 2 targetvalues are larger than the operation voltage.
 15. The method accordingto claim 12, wherein a power analyzer is used to perform the first powerdiagnostics by analyzing at least one of voltage drops of the PDN and aground bounce noise.
 16. The method according to claim 12, wherein theinterconnection has a segment between each two adjacent nodes, and thesegments have the same or different metal width, and the interconnectioncomprises horizontal metal segment, vertical metal segment, diagonalmetal segment, or the combination thereof.
 17. The method according toclaim 12, wherein the nodes of the interconnection are located indifferent metal layers.
 18. The method according to claim 12, whereineach of the at least three subsets are further divided into at leastthree subsets.
 19. The method according to claim 12, wherein the nodesof the interconnection are selected from the group consisting of I/Opads, rings, strips, bumps, rails, Through silicon vias, and thecombination thereof.
 20. The method according to claim 12, wherein theinterconnection is formed according to a circuit design rule or a designrule checking, or further according to a design rule of nodes connectionamong different metals.
 21. The method according to claim 12, furthercomprising: performing a second power diagnostics after theinterconnection is formed, and repeating above steps to generate anotherinterconnection with at least three nodes connected orderly in the PDNaccordingly.
 22. The method according to claim 12, wherein the nodes ofthe interconnection are connected according to the order of the areas,and the interconnection has the characteristics of a surface.